1. Field of the Invention
The present invention pertains generally to valves for physical transport and isolation of liquids and gases. More particularly, the present invention pertains to solenoid-operated isolation valves that are designed for low power and quick dispensing applications. The present invention, in a preferred embodiment, is particularly but not exclusively, useful as a solenoid-operated valve for micro-fluidic platforms with high-density manifolds, and method of manufacturing the same.
2. Description of the Prior Art
Solenoid-operated valves for isolation and transport of fluids are well known. An attractive characteristic of all solenoid-operated valves is that they can be remotely operated because electrical power is used to actuate the valve. Also, a solenoid valve is an attractive option when fluid systems require a valve to cycle open and shut, and thereby pass a set dispense volume of fluid. This is because solenoid valves use a generated and collapsing electromagnetic field to engage a valve stem or a plunger rod. Thus, a power supply can be easily cycled on and off to pass a particular amount of fluid. Solenoid valves are particularly useful in micro-fluidic applications.
Advancements in micro-fluidic arts such as blood chemistry analysis, drug discovery, DNA sequencing, liquid chromatography and other technical arts requiring precision fluid handling have created a need for progress in the components that control and dispense the fluids. Thus a need exists for a design and method for making and using a solenoid valve that provides for small dispensing volumes and can occupy a high density valve manifold with small fluidic components. Also, the nature of most micro-fluidic applications places importance on conserving a fluid sample. Therefore, a valve design and method having a zero “dead volume,” and small internal volume is desired. Similarly, an isolation valve should be designed for zero leakage.
In addition, solenoid valve design and method that requires only a small power supply is desired for several reasons. One such reason is that a solenoid coil energized with a relatively high power supply incurs residual magnetism. Any residual magnetism affects the shut off speed of the valve and therefore the dispensed volume. Also, corrosion properties of materials used to fabricate valves are important. For instance, blood is a natural oxidizing agent and will cause some material to undergo pitting corrosion.